Melamine (2,4,6-triamino-1,3,5-triazine) is mainly used in the synthesis of melamine resins, the latter is widely used in industry for its heat tolerance to produce kitchenware, flame retardants, commercial filters, etc. Melamine was also found as a metabolite of the pesticide cyromazine in plants, goats, hens and rats and is used in some fertilizers. Due to the widespread use of melamine, trace levels may be detected in food, although it is not a kind of food stuffs and additives, and it is forbidden to add to any foods by authorities of any country. Although melamine has a low acute toxicity, it is still thought of as the factor which causes bladder stones, and experimental studies have also shown that combination with cyanuric acid leads to crystal formation and subsequently causes kidney stones.
The compound is an indirect food additive, and there is an increasing concern about the detection of melamine in foods following the pet food incident in 2007 and melamine-tainted formula incident in 2008, which involved the intentional adulteration of protein ingredients used in milk products with melamine to make the products appear to contain a higher protein content than they actually did.
After the pet food incident in 2007 and melamine-tainted formula incident in 2008, many standards were stipulated and amended by different countries and areas. On Nov. 29, 2008, the U.S. Food and Drug Administration (FDA) set a threshold of 1 part per million of melamine in formula, provided cyanuric acid is not also present, instead of the old announcement of no safe level of melamine in baby formula. For all other foods, only amounts less than 2.5 parts per million (ppm) are risk free. In China, 2.5 mg per one kilogram (mg/kg) standard for adult foods and 1.0 mg per one kilogram (mg/kg) for formula has been set. This safety standard is currently widely accepted around the world to address situations in which the chemical accidentally comes into contact with circumstances. In fact, the concentrations of melamine detected in contaminated formulas were extraordinarily high, as much as 2,500 parts per million.
At present, many detection methods of melamine have been reported. The popular methods are HPLC-MS, GC-MS, and HPLC-UV, and ELISA, Et al. Although HPLC, GC and GC-MC are fast and accurate, they are costly. ELISA is limited with its accuracy. Simple, accurate, and rapid detection methods are still urgently needed for the short shelf-time of fresh milk.